Lead pressing



P 1932- c. E. BENNIETT LEAD PRES'SING Filed March 1, 1932 INVENTOR. Wm. M

ATTORNEYS.

Patented Sept. 27, 1932 UNITED STATES PATENT OFFICE CHARLES E. BENNETT, OF HAWTHORNE, NEW JERSEY, ASSIGNOR TO THE OKONITE- CALLENDER CABLE COMPANY, INCORPORATE), OF PATERSON, NEW JERSEY, A

CORPORATION OF NEW JERSEY LEAD PRESSING Appilcation filed March 1,

The present invention relates to an improvement in lead pressing apparatus and methods, and has for one of its objects the provision of a method as well as an apparatus whereby the working of lead and like materials is greatly improved.

In the sheathing of electric cables for instance, which is an intermittent operation, the cable is fed through the dies of the press as the molten lead or other material is forced thereto, until the charge in the heating pot is exhausted, or nearly so. A small portion of the charge, however, is necessarily left in the pot and in the passage or passages leading to the die. The press is stopped until a fresh charge of molten material is supplied to the reservoir or pot. During the interval between the stopping of the press and resumption of operations, that part of the charge remaining in the press cools to a plastic or semi-solid condition and the upper surface of this slug becomes oxidized. The effect of this is that when a fresh charge of molten lead is placed in the pot an imperfect union or weld is obtained, on resumption of operations, betweenthe old charge or slug and the fresh charge. This 'imperfect weld or union is recognized in this art and various methods have been tried to overcome it. I have determined to my own satisfaction that the reason for the imperfect union between the two charges is the presence of the oxides which form on the exposed surface of the old charge or slug. With this in mind, therefore, I have provided a method whereby this dross may be removed in a practicable manner, and I have actually produced welds or unions which cannot be seen under the microscope.

My improved method consists in melting the exposed surface of the slug and then flowing the next charge of molten lead or other material into the machine, the oxides and other impurities, which I shall term dross and which float upon the molten surface of the slug simply rising or floating to the top of the fresh charge, so that I have pure lead to pure lead at the seam or union and hence will obtain a homogeneous perfect bond or union. This melting of the exposed 1932. Serial N0. 595,990.

oxidized surface of the slug of the preceding charge may be produced in a variety of ways. I have tried successfully an electric are, an electric arc in a hydrogen flame and }metal billets such as steel heated to a white eat.

The drawing shows in part sectional .ele vation one embodiment of a suitable apparatus for the practice of my invention.

Referring to the drawing in detail, 1 designates the die blocks of a lead press, for instance, of usual construction. 2 is the pot or reservoir for the molten material. 3 is the usual fixed plunger rfor forcing the molten lead to the die blocks 1, the die blocks and pot being raised, as usual, by hydraulic ram 4, the molten lead being forced to the die blocks under several tons pressure.-

In the operation of such a machine the ram 4 is raised until the plunger or piston 3 forces the bulk of the molten lead out of the pot 2. However, there is always a small amount of lead left in the pot, and of course the passageway from the pot to the die will be left filled. This part of the charge is termed a slug in the lead press art.

After the first run of the press the pot and die blocks are lowered, and a new charge of molten lead dumped into the. pot. In the meantime the slug 5 has cooled below a molten temperature and may be considered in a plastic or semi-solid state, and in this cooling operation oxides and other materials accumulate or form on the upper exposed surface of the slug. Accordingly when a fresh charge is dumped into the pot this dross prevents a good seam orweld between the leads of the two charges.

To overcome this imperfect bonding, I propose to melt the upper surface of the slug 5 before the next lot of molten lead is charged. In the drawing I have shown a billet for this purpose. This billet is heated to the necessary temperature, to white heat if desired, and then lowered into the pot 2, if necessary into contact with the surface of the slug 5. In any event the surface of the slug to an appreciable depth is reduced to a molten con-' dition and upon withdrawal of the billet while this surfaceis still in this condition a fresh charge of lead is flowed into the pot, this fresh charge as it flows in displacing the dross on the molten surface of the slug the dross simply rising or floating to the top of 5 the fresh charge. Consequently I have pure lead to pure lead, and am assured of a perfect bond or union. As a matter of fact I have obtained such excellent results in practicing my invention, using a steel billet for melting m the surface of the slug, that the same is not visible under a microscope.

As above mentioned instead of the heating means shown, I may employ an electric arc,- an arc in a hydrogen flame or other suitable heating device or arrangement which will produce the desired melting of the surface of the slug.

What I claim is 1. In lead pressing the method which comprises applying pressure to a molten lead charge to force a portion of the same through a die, relieving the pressure on the charge, then applying heat to the surface of the remainder of the charge until said surface be comes molten, and while the surface is in a molten state imposing a fresh charge of molten lead upon the same to displace the dross carried thereby, and then applying pressure to the fresh charge to form a homogeneous bond or union between the two charges.

2. In combination an extruding press provided with an open reservoir for molten material, pressure means for forcing a portion of the molten char e out of the reservoir to a die, and means or applying" heat to the exposed surface of that portion of the charge remaining in. the reservoir after the withdrawal of the said pressure means and before the introduction of a fresh charge of molten material into the reservoir to" reduce the said exposed surface to a molten condition, whereby introduction of the fresh molten charge will displace the dross carried on the said molten surface of the preceding charge.

This specification signed this 27th day of February, 1932. CHARLES E. BENNETT. 

